Abstract: The short-term effects of different application rates of straw biochar on soil nutrients and the diversity of bacterial communities were studied in order to provide instruction for improvement of tobacco-planting soil and rational utilization of straw resources in Baoshan of Yunan province. The field experiment in 2019 was constituted of three treatments:1) CK, conventional fertilization, 2) T1, CK+ straw biochar 4.5 t/ha, and 3) T2, CK +straw biochar 9 t/ha. The values of soil pH, organic matter, available nutrient contents and bacterial community diversity were measured and compared. The results were as follows. 1) Compared with CK, the contents of organic matter, alkeline-N, rapid available P and rapid available K were significantly increased in 0-20 cm layers but decreased in 40-60 cm layers in T1 and T2. 2) Compared with CK, the bacterial composition of T1 and T2 was more similar. The OTU numbers of both samples were significantly increased by 28.59% and 33.82%, respectively. However, the abundance and diversity of bacterial communities in T2 were higher than CK. 3)The top three dominant soil bacterial communities in relative abundance had significant positive correlation with available P and rapid available K of the soil. In a conclusion, the application amount of straw biochar can significantly improve soil fertility and diversity of bacterial communities of tobacco-planting soil, and the conventional fertilization with 9 t/ha straw biochar is better, but the interaction mechanism between soil nutrients and microorganisms after biochar application should be further studied.